THE ANCIENT GREEKS
Around the 6th century BCE, several Greek colonies were formed on the Black Sea coast.
The colonies facilitated the trade relations between the Thracians living in the interior and the Hellenic World. The cities of Apollonia (modern day Sozopol), Mesembria (modern day Nesebar), and Odessos (modern day Varna) date back to that period. Many continued to have a sizeable Greek-speaking population as late as the early 20th century.
The colonies brought commercial and cultural benefits to the Thracians living in the interior, but forever cut the chances of the Thracians, and later the Bulgarians, of becoming a sea-faring power.
ALEXANDER THE GREAT AND THE THRACIANS
After a brief Persian invasion in the 6th century BCE, Philip of Macedon, and later his son Alexander the Great, conquered the land of the Thracians in the 4th century BCE. New cities were founded, most notably Philippopolis or the city of Philip (modern day Plovdiv).
Despite the invaders, the Thracians away from the Black Sea coast lived relatively undisturbed. The Thracian Odrysian state and its most famous ruler, Seuthes III, date from that period.
Alexander’s vast empire disseminated shortly after his death. The following period of chaos was used by the Celts to invade the Thracian lands on their way to Greece and modern day Turkey, and left a mark on Thracian life and culture.
In the 1st century BCE, the Bulgarian lands became part of the Roman Empire, forming the province of Moesia.
The Odrysian kingdom continued to exist as a Roman ally until the middle of the century when it was turned into the Roman province of Thracia.
Rome had serious geopolitical plans for the region and was determined to establish a lasting presence. The Romans fortified many of the Thracian settlements and build many new towns and cities. Modern day Stara Zagora (Augusta Traiana) and modern day Devnya (Marcianopolis) date back to that period.
Emperor Mark Ulpius Traianus was most involved with the infrastructure projects in the provinces of Thracia and Moesia, and commissioned many of the building works. Some cities were named after him. For example, the Thracian city of Serdica (modern day Sofia) became Ulpia Serdica in his honor.
Some of the city-building energy of the Romans must have come from the abundance of hot mineral springs in all those sites. This must have been a blessing for the Romans who were devoted bathers. The major road arteries of the Balkan Peninsula also date back to Roman times.
Waves of immigrants settled in the land bringing their customs and beliefs with them. The indigenous Thracian population was gradually romanized and later intermingled with the waves of Slavic people arriving to the Balkans as of the 5th century.